In Private Branch Exchange (PBX) systems, an attendant processes incoming calls separately and independently of one another. Frequently, an attendant may be awaiting a response on a first-incoming call at an attendant facility when a second-incoming call appears at the facility. When the condition occurs, the attendant may (1) place the first call in a hold mode and then process the second call or (2) ignore the second-incoming call until the first-incoming call has been completed. If the attendant chooses the first alternative, the first-incoming call may be lost unless the party on the call is informed of being placed into the hold mode. If the attendant chooses the second alternative, the second-incoming call may be lost.
In one known system, key telephones were modified to enable the attendant to monitor a plurality of lines simultaneously without the capability of conversing. The system also included two-way circuits for conversation. Therefore, the attendant could monitor only a plurality of lines while conversing on a separate two-way circuit. This system requires a separate line for each call that is being monitored as well as a separate line for the two-way circuit. Moreover, this system does not allow conversation between a party whose call is being monitored and the attendant.
Consequently, to prevent the occurrence of either of the dilemas mentioned above without requiring separate lines, there is a need for methods of and systems for allowing an attendant to (1) process the second-incoming call while monitoring the progress of the first-incoming call and (2) return to the first-incoming call when necessary.